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The prime meridian of the Moon lies directly in the middle of the face of the Moon visible from Earth and passes near the crater Bruce. The prime meridian of Mars was established in 1971 [35] and passes through the center of the crater Airy-0, although it is fixed by the longitude of the Viking 1 lander, which is defined to be 47.95137°W. [36]
On the question of universal time, Fleming's opinion to one of the lead-up committees was borne out: "In my judgment, the nearest approach to it which may be attempted with any chance of success, is to have first, a primary standard time, based on the prime meridian that is to be used for non-local purposes; second, to have twenty-four ...
A time zone is an area which observes a uniform standard time for legal, commercial and social purposes. ... For example, even though the Prime Meridian ...
From 1884 to 1974, the Greenwich meridian was the international standard prime meridian, used worldwide for timekeeping and navigation. The modern standard, the IERS Reference Meridian, is based on the Greenwich meridian, but differs slightly from it. [1] This prime meridian (at the time, one of many) was first established by Sir George Airy ...
The conference therefore established the Greenwich Meridian as the prime meridian and Greenwich Mean Time (GMT) as the world's time standard. The U.S. time-zone system grew from this, in which all zones referred back to GMT on the prime meridian. [2]
Greenwich Mean Time is defined in law as standard time in the following countries and areas, which also advance their clocks one hour (GMT+1) in summer. United Kingdom, where the summer time is called British Summer Time (BST) Ireland, where it is called Winter Time, [22] changing to Standard Time in summer. [21] Portugal (with the exception of ...
In theory, ships are supposed to adopt the standard time of a country if they are within its territorial waters within 12 nautical miles (14 mi; 22 km) of land, then revert to international time zones (15° wide pole-to-pole gores) as soon as they leave. In practice, ships use these time zones only for radio communication and similar purposes.
Worldwide time zones at present. Standard time is the synchronization of clocks within a geographical region to a single time standard, rather than a local mean time standard. Generally, standard time agrees with the local mean time at some meridian that passes through the region, often near the centre of the region.